In order to meet the demand of large bandwidth and high speed mobile access increasing day by day, the Third Generation Partnership Projects (abbreviated as 3GPP) brings out the Long-Term Evolution advance (abbreviated as LTE-Advanced) standard. The LTE-Advanced reserves the core of the Long-Term Evolution (abbreviated as LTE) for the evolution of the LTE, and on that basis adopts a series of technologies to extend a frequency domain and a space domain, so as to achieve the purposes, such as improving the spectral efficiency, increasing the system capacity, etc.
A wireless relay technology is one of the LTE-Advanced technologies, aimed at extending the coverage area of a cell, reducing the dead corner area in communication, balancing the load, transferring services of the hot spot area and saving the transmission power of a User Equipment (abbreviated as UE). A Relay Node (abbreviated as RN) provides functions and services similar to a common eNB to the UE which accesses the cell of the RN, and accesses, through a wireless interface and in a manner that the RN is similar to a common UE, to one eNB which serves the RN, wherein the eNB which serves the RN is called a Donor eNB, abbreviated as DeNB. The DeNB is connected with a Mobility Management Entity (abbreviated as MME). Functions that the MME provides for the UE include: processes of control signalings, such as, user access control, authentication, data encryption, service bearer control, paging, handover control, etc. Multiple MMEs serve a public geographical area together, and in the geographical area, the eNB and/or the DeNB (hereafter referred to as eNB/DeNB) connect to the multiple MMEs in that geographical area with a net structure. A set of MMEs in that public geographical area forms a MME pool, and the area is also called as a MME pool area, corresponding to several tracking areas (abbreviated as TA); and the UE does not need to change the served MME when moving in these tracking areas.
As the high-speed railway is built and put into operation on a large scale, the demand for communicating on a train is increasing constantly. The practical speed of the high-speed railway has already reached 350 kilometers per hour at present, and it is very difficult that the coverage of base stations in the existing network meets communication quality demand of the high-speed railway by suffering the influence, such as, Doppler frequency shift, cell handover frequently, high penetration loss of the high-speed railway carriage, etc. So the industry proposes deploying the relay node on the high-speed railway, as shown in FIG. 1, which lets users, such as UE1 and UE2, in the high-speed railway train directly communicate with the RN which is rest relative to the UEs, and the RN can perform handover among different DeNBs in the process of the high-speed railway moving, thereby avoiding the simultaneous handover of a large number of users in the carriage of the high-speed railway and guaranteeing the communication quality between the UEs and the RN. In addition, by enhancing the backbone connection between the mobile RN and the DeNBs, it can better solve the above-mentioned problem existed in the high-speed railway. But the introduction of the mobile RN will produce a great impact on the relevant standard of the RN in the existing LTE-Advanced.
For example, for an RN cell, an Operation and Maintenance (OAM) entity usually configures information of a TA area to which the cell belongs, and the RN cell broadcasts the TA to which the cell belongs in a form of Tracking Area Code (TAC) in a System Information Block Type1 (SIB1). On the other hand, after starting up, the UE can only accept the services after registering to the network at first; in the process of registering, the MME that the UE connects allocates a tracking area identification list (TAI list) for the UE, wherein the tracking area identification includes a Public Land Mobile Network (PLMN) identification and a TAC. If the UE selects or re-selects one RN cell, and finds that the TA to which the RN cell belongs is not in the TAI list registered by the UE according to the SIB1 message broadcasted by the RN, then the UE needs to perform a process of Tracking Area Update (abbreviated as TAU) to inform the MME about the current location and update the registered TAI list correspondingly. When there are arrived downlink data corresponding to the UE, the MME of the UE can send a paging message to all eNB/DeNBs covered by the tracking area included in the list according to the TAI list of the UE. After receiving the paging message, the eNB/DeNB judges one by one whether the TA of each cell (including the RN cell) is consistent with the TAI information included in the TAI list, and if yes, then pages the UE by the paging message through an air interface on the corresponding cell. Once receiving the corresponding paging message at the air interface, the UE performs a service request process, and transfers to a connection state. After the process is finished, the S-GW sends the data to the eNB currently connected to the UE and the UE.
In the process of the RN moving, how to configure the TAC of the RN and how to keep accordance with the current connected DeNB need to be reconsidered; if the configuration is improper, it will cause new problems related to the tracking area update of the mobile relay and the paging. For example, in the process of the RN moving, if the TAC of the RN changes with the change of the TAC of the target DeNB, this will cause that, in the process of the RN moving, the UE served by the RN constantly detects that the TA of the RN is inconsistent with the TAI list registered by the UE, thus a large amount of UEs perform the TAU at the same time, which leads to signaling block. On the other hand, under a scenario that the TAC of the RN maintains unchanged in the whole movement process while the DeNB does not include the TA of the RN, the MME which serves the UE does not probably know the TA to which the new RN served by the DeNB belongs, and it does not send the paging information to the DeNB, thereby being unable to page the UE.